The present invention relates to a cosmetic composition comprising N-acetylglutamine.
Owing to external factors such as ultraviolet rays and dryness and physical factors such as aging, natural moisturizing factor (NMF) inherently held by the skin gradually decreases and thereby the skin becomes dry and rough. In order to provide a cosmetic composition effective for keeping the skin fresh and moist, use of amino acids and derivatives thereof which are the major components of NMF as a cosmetic base has been studied.
There are disclosed, for example, glutamine (IN Patent No. 137275), glutamic acid, acetylglutamic acid (U.S. Pat. No. 3,932,622), N-acylglutamic acid esters containing an acyl group having 7 to 21 carbon atoms (Japanese Published Unexamined Patent Application No. 67443/73), N-acyl-acidic amino acid esters containing an acyl group having 2 to 22 carbon atoms (Japanese Published Unexamined Patent Application No. 37839/79), N-lower acyl-acidic amino acid diesters containing an acyl group having 1 to 7 carbon atoms (Japanese Published Unexamined Patent Application No. 92237/74), N,N'-diacyl-basic amino acid esters containing an acyl group having 8 to 22 carbon atoms (Japanese Published Unexamined Patent Application No. 19138/76), etc. However, use of these substances as a cosmetic base has various drawbacks; for instance, they feel poor when they are applied to the skin, they irritate the skin, and an acetic acid odor is emanated during storage over a long period of time.
N-Acetylglutamine used in the present invention is an N-acetylated derivative of glutamine which is known to be excellent in heat stability compared to glutamine (Japanese Published Examined Patent Application No. 670/72).
In addition, the present substance is excellent in safety [KISO-TO-RINSHO (Basis and Clinic, Vol. 8, No. 4, Apr., 891-898 (1974)] and its aluminum salt has been used as an anti-ulcer agent for medical treatment [Folia Pharmacol. Japon, 68, 602-617 (1972)]. However, there has been no report on utilization of N-acetylglutamine as a cosmetic base.